Drayton SM2 replace with LP241 - wiring issue

[brendan1978]

Hi all, got a noob question, we cannot get a engineer out for weeks to do this job, so having replaced programmers before i thought i would replace our noisy SM2 with a LP241, knowing that the plates are identical... thought this would be simple... however!

The SM2 is currently wire up as follows

N - neutral

L - Live

1 - Blank

2 - Blank

3 - wire

4 - wire

The SM2 has a both CH and HW timers on it, but how can it work when not wired correctly? When i Installed the LP241 onto the plate the boiler appeared permanently on... sooo was wondering if anyone can shed light on this for me. Thanks

There is a Thermostat - the CH is a sealed system - I can take pics if this helps

 

[NozSpark]

Without looking for the installation manuals,,,

1 & 2 are normally HW & CH OFF and

3 & 4 are HW & CH ON

HTH

 

[Andy™]

the plate may be the same, but the connections may not be. look on the back of both at the wiring diagram and you should be able to work out what goes where.

you also need to set the swithc in the back of the LP241 to tell it if its gravity or pumped

---------- Post Auto-Merged at 22:16 ---------- Previous post was made at 22:14 ----------

just looked and both have the same internal wiring, so should be a straight swap

why did you change it in the first place?

 

[Nicky Tesla]

he said it was noisy

 

[brendan1978]

Aye both wiring should be the same, N and L 1 = HW off 2 = CH off 3 = HW on 4 = CH on

Changing it cause the SM2 is sooooooo noisy and annoying, plus with a baby we rather to have the ability to turn the CH on for a 3rd time in a single day.

When I swapped it before the LP241 worked right away, however the boiler kicked in while both channels were turned off :S

 

[Doc Hudson]

If it was working correctly with the old programmer it should work with the new one according to Draytons compatibility charts?

www.draytoncontrols.co.uk/D70_8_LP_Boost_Compatibility.aspx

Doc H.

---------- Post Auto-Merged at 22:30 ---------- Previous post was made at 22:28 ----------

Another coincidental fault, have you tried putting the old one back on do the symptoms go?

Doc H.

 

[brendan1978]

Aye have put the old one back on, but now noticed that the HW is always hot when the CH is on!!? pipe tracing shows the boiler has just a in and out water feed, which then in turn feeds the CH and HW at a Tee and both systems have pumps. I dont think the SM2 HW timer or ON switch actually do anything! confused now haha

 

[Andy™]

if HW is now hot when CH is on, youve probably knocked the switch on the back

 

[SPECIAL LOCATION]

Aye have put the old one back on, but now noticed that the HW is always hot when the CH is on!!? pipe tracing shows the boiler has just a in and out water feed, which then in turn feeds the CH and HW at a Tee and both systems have pumps. I dont think the SM2 HW timer or ON switch actually do anything! confused now haha

2 x Pumps?

No valves? :C

I was going to suggest a sticking valve........

BUT...

If you aint got none!!!!!!!! :C

 

[batty]

sounds like you need a plumbit to put a few valves in so you can actually control were hot water is going otherwise system will be very costly.

 

[the_mouse]

The heating system is SMC, are these programmers compatible with this system?? The one I replaced recently had to have an external relay to control the boiler with a horseman c27 programmer.

Sent from my iPhone using Tapatalk

 

[wozz]

Diagram half way down here may help, I changed a programmer on a similar system recently what a PITA, not helped by bathroom fitter putting towel rail on wrong circuit.

Fully Pumped Systems

 

[Doc Hudson]

The heating system is SMC, are these programmers compatible with this system?? The one I replaced recently had to have an external relay to control the boiler with a horseman c27 programmer. Sent from my iPhone using Tapatalk

Diagram half way down here may help, I changed a programmer on a similar system recently what a PITA, not helped by bathroom fitter putting towel rail on wrong circuit.Fully Pumped Systems

Interesting points, if correct I cannot see how the original 'noisy' timer worked before, as the two timers have identical outputs on the back plate?

Doc H.